Apparatus for detecting traces of heavy combustible gases and heating systems incorporating such apparatus

ABSTRACT

An arrangement for detecting traces of heavy combustible gases constituted by a gas burner fed with a combustible gas similar to that which is to be detected and with combustive air tapped out of the atmosphere to be detected, said burner being adjusted in a manner such that its flame is metastable and released and extinguished as soon as the contents of combustible gas in the air thus tapped off and thereby in the mixture fed into the burner rise up to a predetermined figure.

United States Patent Inventor Bernard Faure 10, Boulevard dlnkermann, Neuilly-sur- Seine, Hauts-de-Seine, France Appl. No. 833,385 Filed June 16, 1969 Patented June 1, 1971 Priority June 28, 1968 France 157,121

APPARATUS FOR DETECTING TRACES 0F HEAVY COMBUSTIBLE GASES AND HEATING SYSTEMS INCORPORATING SUCH APPARATUS 5 Claims, 3 Drawing Figs.

Int. Cl F23n 5/24 Field of Search 431/16, 22, 51, 89

n 13,ss2,247

[56] References Cited UNITED STATES PATENTS 1,997,797 4/1935 Kelley 431/22 2,585,882 2/1952 Weissman et al.... 1. 431/16X 3,236,284 2/1966 Kemper 431/22X Primary ExaminerEdward G. Favors Attorney-Pierce, Scheffler and Parker COMBUSTIBLE GASES AND HEATING SYSTEMS INCORPORATING SUCH APPARATUS The present invention has for its object a gas burner applicable as an atmosphere testing apparatus with a view to detecting traces of heavy combustible gases such for instance as liquefied petroleum gases.

Such gases chiefly butane and propane have a specific weight above that of air and their use is dangerous since they lead to the risk in the case of a leak of producing a stagnant sheet over the ground. Such a risk has led to the drafting of safety rules forbidding in fact in certain countries the use of these gases in those premises the lower part of which cannot r, be reliably ventilated. This is the case of cellars and basements in which are generally fitted in fact central heating boilers. The problem thus laid open prevents the development of central heating system resorting to liquefied petroleum gases more particularly in the case of domestic and commercial appliances which would otherwise lead to a large consumption of petroleum products.

The presenti'nvention has for its object a solution for such a problem asprovided, by simple means adapted to detect the sheet of gases arising when a leak occurs fortuitously and to stop immediately thereupon the operation of the apparatus fed with a combustible gas.

Applicants investigations as to atmosphere testing burners as disclosed in the French Pat. No. 1,158,557 dated Sept. 14, 1956 entitled Safetybur'ner and its addition 71,721 dated June 12, 1957 have led to the following conclusions:

Such a burner may be adjusted in a manner such that in the presence of a pure atmosphere the flame is at the limit of its stability while it moves off the nozzle and vanishes as soon as the air supplied to it shows lower contents of combustive matter. The metastable adjustment considered is obtained by adjusting the output speed of the mixture of air and gas so that it may be slightly below the speed of propagation of the flame in the mixture considered within a pure atmosphere. When the contents of combustive air in the mixturedecrease said speed of propagation decreases and when it sinks underneath the speed at which the mixture flows the flame moves off the nozzle and is extinguished.

Applicant has executed experiments on a burner provided with an injector of a diameter of 0.1675 mm. and a nozzle of 4.8 mm. and it has been found that the speed forwhich the flame is released was reached for a proportion of air and gas in the mixture feeding the burner which corresponds to 75 percent of the proportion of air in the stoechimetric mixture. For such a proportion the mixture contains 22.12 litres of air for each litre of butane.

Now if the air reaching the burner is laden with a small amount of butane as may occur in the case ofa leak, say in the proportion of 0.5 percent that is 0.1 1 litre for 22.12 litres of air, the composition of the mixture fed to the burner becomes 22.0! litres of air (22.l2-0.1 1) for 1.11 litres of butane (l+().11). In other words the mixture includes 19.83 litres of air for l litre'of butane.

Consequently the presence of traces of butane in the ambient atmosphere in the proportion of five parts for one thousand is equivalent to a reduction of percent in the air contents. Thus, the burner is of a high sensitivity in the .presence of traces of combustible gas and may serve for detecting leaks of the latter.

The present invention has also for its object a central heating burner to be erected underground and which is provided with safety means operating in the case ofa leaking ofa heavy combustible gas.

The accompanying drawings illustrate by way of example an embodiment of the invention whereby an easy understanding ofthe invention may be obtained. In said drawings:

FIG. 1 is a general view of an underground central heating system,

, FIG. 2 is a view of a detail of said central heating system,

FIG. 3 illustrates'a further detail.

Turning to the system illustrated in FIG. 1, the boiler 1 erected in the basement 2 of a house is fed with fuel constituted by liquefied gas carried in a tank 3 located outside the house, the feeding with combustive air being ensured through the ventilator 4. l

The combustible gas is fed from the tank 3 through the channel 5 to the safety block 6 and thence through the channel 7 to the boiler l. The safety block 6 is connected through the channel 8 with a collector 9 lying on the basement floor and adapted to suck in air from the lowermost point of the premises, said collector communicating with the smoke exhaust channel 10 passing out of the safety block 6.

The safety block 6 described with further detail hereinafter with reference to FIG. 3 includes a safety burner 15 fed with combustible gas through the above-mentioned channel 5 and with combustive air through said channel 8.

Any possible leak of combustible material forms a sheet extending over the lowermost surface of the basement and consequently the basement air should be tapped off at a point as low as possible. To this end the channel 8 is connected with the collector 9 constituted as illustrated in FIG. 2 by a bellshaped member 11 including an antideflagrating grid-shaped screen 12 the spacing of which above ground is adjusted by three feet-forming screws 13.

A suction is produced inside said bell-shaped member by the caseof aburner 15 which shows the above-mentioned features, the total energy dissipated by said burner is equal to 77 millithermies per hour while the volumeof air sucked in is of a magnitude of 30 to 35 cub. cm. per hour.

Turning to FIG. 3, it is apparent that the safety block includes a fluidtight casing 14 connected on the one hand with the air-tapping channel 8 and on the other hand with the exhaust channel 10. In said casing is fitted the safety burner 15 which is adjusted in a manner well known per se so as to lie on the boundary of stability. Said burner 15 is fed with combustible gas through a thermostatically controlled cock 16 which is fed in its turn with said gas through the channel 5 feeding also the channel Heading to the' boiler 1. Said burner 15 lies within an antideflagrating chamber subdivided into two compartments. The lower compartment 26 surrounds the opening 17 through which primary air reaches the burner 15 while the upper compartment '19 surrounds the area in which the flame 18 is obtained said latter compartment being connected with a tapping 20 feeding external air and said tapping being preferably also provided with an antideflagrating grid and with a flap adapted to adjust the operative area of said tapping.

A generator of high voltage 21 controlled by a handle 22 is connected with an electrode 23 by a wire 24 so as to supply a spark for the ignition of the burner without it being necessary to open the antideflagrating chamber.

The bulb 25 of the thermostat controlling the cock 16 is subjected to the action of the flame 18 and its heating'provides for the actual opening of the cock 16 which feeds combustible gas to the boiler l and to the detecting burner 15. Said burner 15 is thus fed with combustive air tapped out of the lower layers of the atmosphere in the basement 12 and whenever said combustive air carries traces of combustible gas the flame vanishes and this controls the stopping of the operation of the boiler.

What I claim is:

1. In combination with heating boilers and the like apparatus including a pipe feeding it with a combustible fluid, an arrangement adapted to detect leaks of said combustible fluid and comprising a safety burner producing a flame adapted to become extinguished whenever traces of fuel in the primary air fed to said burner raise the contents of fuel in the primary air and fuel mixture fed to the burner above a predetermined threshold, means feeding the burner with a combustible fluid similar to that feeding said apparatus and means feeding said burner with primary air tapped out of the area surrounding said apparatus.

2. An apparatus as claimed in claim 1 wherein last-mentioned means include means collecting samples of air out of the area surrounding the apparatus, a channel connecting said collector with the external atmosphere and subjected to the draft produced by the burner flame, means through which said channel feeds the air from the collector into the burner to form the primary air for the latter.

3. An apparatus as claimed in claim 1 wherein last-mentioned means include means collecting samples of air out of the area surrounding the apparatus, a channel connecting said collector with the external atmosphere and subjected to the draft produced by the burner flame, means through which said channel feeds the air from the collector into the burner to form the primary air for the latter, an outer fluidtight chamber inserted in said channel in registry with the burner, means feeding combustible gas both into the pipe feeding the apparatus and into the means feeding the burner, a cock inserted in last-mentioned feeding means adapted to stop the feed of combustible fluid, a thermostat controlled by the burner flame and controlling the cock to make the latter stop the feed of combustible fluid upon extinction of the burner flame.

4. An apparatus as claimed in claim I wherein last-mentioned means include means collecting samples of air out of the area surrounding the apparatus, a channel connecting said collector with the external atmosphere and subjected to the draft produced by the burner flame, means through which said channel feeds the air from the collector into the burner to form the primary air for the latter, an outer fluidtight chamber inserted in said channel in registry with the burner, means feeding combustible gas both into the pipe feeding the apparatus and into the means feeding the burner, a cock inserted in last-mentioned means adapted to stop the feed of combustible fluid, a thermostat controlled by the burner flame and con: trolling the cock to make the latter stop the feed of combustible fluid upon extinction of the burner flame and an inner antideflagrating chamber surrounding the burner inside the outer chamber and through which the burner receives its secondary air from the outer atmosphere.

5. An apparatus a as claimed in claim 1 adapted to be inserted between a tank carrying the combustible fluid and located outside the premises housing the apparatus and the pipe feeding the latter, wherein last-mentioned means include means collecting samples of air out of the area surrouading the apparatus, a channel connecting said collector with the external atmospheric and subjected to the draft produced by the burner flame, means through which said channel feeds the air from the collector into the burner to form the primary air for the latter, an outer fluidtight chamber inserted in said channel in registry with the burner, means feeding combustible gas both into the pipe feeding the apparatus and into the means feeding the burner, a cock inserted in last-mentioned feeding means, fed by the tank and adapted to stop the feed of combustible fluid, a thermostat controlled by the burner flame and controlling the cock to make the latter stop the feed of combustible fluid upon extinction of the burner flame. 

2. An apparatus as claimed in claim 1 wherein last-mentioned means include means collecting samples of air out of the area surrounding the apparatus, a channel connecting said collector with the external atmosphere and subjected to the draft produced by the burner flame, means through which said channel feeds the air from the collector into the burner to form the primary air for the latter.
 3. An apparatus as claimed in claim 1 wherein last-mentioned means include means collecting samples of air out of the area surrounding the apparatus, a channel connecting said collector with the external atmosphere and subjected to the draft produced by the burner flame, means through which said channel feeds the air from the collector into the burner to form the primary air for the latter, an outer fluidtight chamber inserted in said channel in registry with the burner, means feeding combustible gas both into the pipe feeding the apparatus and into the means feeding the burner, a cock inserted in last-mentioned feeding means adapted to stop the feed of combustible fluid, a thermostat controlled by the burner flame and controlling the cock to make the latter stop the feed of combustible fluid upon extinction of the burner flame.
 4. An apparatus as claimed in claim 1 wherein last-mentioned means include means collecting samples of air out of the area surrounding the apparatus, a channel connecting said collector with the external atmosphere and subjected to the draft produced by the burner flame, means through which said channel feeds the air from the collector into the burner to form the primary air for the latter, an outer fluidtight chamber inserted in said channel in registry with the burner, means feeding combustible gas both into the pipe feeding the apparatus and into the means feeding the burner, a cock inserted in last-mentioned means adapted to stop the feed of combustible fluid, a thermostat controlled by the burner flame and controlling the cock to make the latter stop the feed of combustible fluid upon extinction of the burner flame and an inner antideflagrating chamber surrounding the burner inside the outer chamber and through which the burner receives its secondary air from the outer atmosphere.
 5. An apparatus a as claimed in claim 1 adapted to be inserted between a tank carrying the combustible fluid and located outside the premises housing the apparatus and the pipe feeding the latter, wherein last-mentioned means include means collecting samples of air out of the area surrounding the apparatus, a channel connecting said collector with the external atmospheric and subjected to the draft produced by the burner flame, means through which said channel feeds the air from the collector into the burner to form the primary air for the latter, an outer fluidtight chamber inserted in said channel in registry with the burner, means feeding combustible gas both into the pipe feeding the apparatus and into the means feeding the burner, a cock inserted in last-mentioned feeding means, fed by the tank and adapted to stop the feed of combustible fluid, a thermostat controlled by the burner flame and controlling the cock to make the latter stop the feed of combustible fluid upon extinction of the burner flame. 